"I love hitting girls on roller skates," said Kristen "Krissy Crash" Adolfi, laughing. "Where can you find this many powerful women in one place who love kicking the crap out of each other."

"You fall in love with it, getting out aggression, being tough but yet sexy at the same time," another roller derby contestant said.

Roller derby began in the 1930s, but it wasn't until the 1970s that it became "theatrical" and really captured the attention of the country, said Rebecca Ninburg, owner of the LA Dolls Roller Derby.

"In the Depression, there was sort of this revival of these relay races on skates," Ninburg said. "They would start fighting and the crowd would go crazy. It remained popular in the '50s and '60s and the '70s, and in the 70's it started becoming really theatrical."

The rules of the game are simple. There are five players from two teams, each with four blockers and one "jammer," who is identified by a star on her helmet. It's the jammer's job to break through the pack and score points, for which she has 60 seconds.

But what sets this sport apart from others is that hitting is allowed, although there are penalties for illegal hits, such as elbowing. The entire game consists of two halves, each of which has two 12-minute periods.

"There's nothing like going and hitting somebody, having them hit the ground," Jennifer Plum, who goes by the name "Hanna Belle Lector" and plays for the Minnesota RollerGirls, told The Associated Press. "Watching people stand up and scream. It's fantastic."

Roller Derby Girls Say Sport Boosts Self Esteem

And unlike some other sports, there are no boring uniforms: You can find everything from fishnets to short-shorts on the rink. A visit to the makeup room before the game is also a must.

"I can wear bright red lipstick and go out and play because I want to look good while I'm hitting somebody or while I'm taking somebody out," Lyndsay Trader, an education administrator who skates for the Minnesota RollerGirls under the name "Mitzi Massacre," told the AP.

Today, there are roller derby leagues across the country and most of them are owned by skaters and run as non-profit organizations.

"We have secretaries, lawyers, nurses," Ninburg said. "Inherently it's about the sport, about being female and all that it encompasses."

There's even a Facebook petition -- boasting 3,082 members -- to make this sometimes violent game into an Olympic sport.

Roller derby players say the dichotomy of the game is such that it allows them to be feminine and yet let out their aggression at the same time.

"I like being girly and I also like to hit people, so it's the best of both worlds," said Melaine "Pushywhipped" Severns of the LA Dolls.

It's even helped some lose weight and helped boost their self esteem.

"Take everything that it is to be female, be tough, strong, beautiful and be recognized as athletes as well as women," Ninburg said.